I've got a 67 wagon with a few odd noises. First, when you are stopping, and the vehicles weight starts to shift to the front of the vehicle, there is a lot of groaning. Could this be the front suspension bushings making this noise? The other odd noise also concerns braking. When I use the brakes, even at a complete stop, I get a very quiet, but high pitched whistle, almost like a dog whistle. It soulds like it's coming from under the dash, but maybe it's the power assist vacuum thing. I can modulate the pitch of the whistle with slight changes in foot presure. The brakes are great, and stop very straight. I also should mention that the wagon has been converted to dual circuit, with the front circuit ran through a vac assist, and the rear brakes just being non-power. All of these parts seem to be bright shiny new parts, too. Is this a normal conversion?

Thanks!
John